...sign product states just for symmetry reasons. To explain the idea we introduce the concept of exchangeable probability assignments. First we introduce the notion of symmetric probability assignments =-=[41]-=-. Let X1, . . .,Xn be random variabels, each having the value set X. Then a joint distribution on these n variables is called symmetric if P(xπ(1), . . .,xπ(n)) = P(x1, . . .,xn) for every permutation...